Seasonal Variations of Dissolved Organic Matter in the East China Sea Using EEM-PARAFAC and Implications for Carbon and Nutrient Cycling

Zheng, Hao; Yan, Zhishen; Chen, Jianfang; Jin, Haiyan; Chen, Chen‐Tung Arthur; Liu, Maokun; Yan, Zupeng; Ji, Zhongqiang

doi:10.3390/su10051444

Cited by 12 publications

(6 citation statements)

References 57 publications

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“…Although the photodegradation could modify the FDOM indexes during the long-range transport from the Changjiang River, such as significant decreasing the degree of DOM humification and increasing the BIX value of DOM [50][51][52][53] , the values of the indexes between the surface (0 m) and subsurface water (> 0 m) depths in these well-stratified water columns showed no statistically differences (Student's t-test; p-value = 0.06 for HIX, 0.47 for BIX, and 0.35 for FI). In the previous studies, the relatively lower HIX values (< 2) and higher BIX values (> 0.8) already reported near the Changjiang River mouth 54,55 , indicating that the in-situ biological production seems to be a significant origin of DOM in the ECS. Therefore, the FDOM indexes can be proper indicators to suggest the origin of DOM in the Changjiang River water-seawater mixing zone.…”

Section: Discussionmentioning

confidence: 76%

Factors controlling the distributions of dissolved organic matter in the East China Sea during summer

Kim

Park

et al. 2020

Sci Rep

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to determine the distribution of dissolved organic matter (DoM) in the east china Sea (ecS) during the summer, we measured the dissolved organic carbon (DOC) and nitrogen (DON), fluorescent dissolved organic matter (fDoM), and chlorophyll a (chl. a) in the upper 100-m layer of this region during July and September 2015. The DOC (r 2 = 0.72 and 0.78 in July and September, respectively) and DON (r 2 = 0.43 and 0.33) were significantly correlated with salinity, suggesting that the river is the primary origin of DOM. However, we found that at a DOC "pulse" under a salinity ranging from 24 to 35, the extrapolating DOC values (304 ± 11 μM) were twice higher than those with a salinity of close to 0, as found in a previous study. the excess Doc concentration seemed to be attributed to the microbial metabolism during transport from the estuary based on the good relationships between Doc and marine humic-like fDoM (r 2 = 0.42 and 0.47), as well as the fluorescence, humification, and biological indexes, but showed no correlation with chl. a. thus, the results of our study indicate that microbial activities can be a significant factor controlling the distribution of DOM in the ECS during summer. Dissolved organic matter (DOM) in the oceans is one of the largest reservoirs of carbon and nitrogen on Earth, and its distribution and behaviour play crucial roles not only in biogeochemical processes in the ocean but also in the carbon and nitrogen cycles 1. Dissolved organic carbon (DOC), the carbon component of DOM, can be preserved for thousands of years in the deep open oceans with relatively lower and uniform concentrations because more than 90% of DOC is recalcitrant to microbial utilization in the water column 2,3. Thus, this carbon fixed in dissolved organic form could contribute to the sinking of atmospheric CO 2 in the ocean through the biological pump 4,5. By contrast, high and significant variations in DOC concentrations have been found in the coastal and marginal oceans owing to intense biological activities and large terrestrial inputs 6. Dissolved organic nitrogen (DON), the nitrogen component of DOM, including urea, amino acids, nucleic acids, and amino sugars, is a primary reservoir of reactive nitrogen in the oceans. When dissolved inorganic nitrogen (DIN) is depleted, DON is the dominant pool of fixed nitrogen, and can become a direct energy source for marine microorganisms 7. By the microbial carbon pump, microbial transformation of DOM from labile to recalcitrant state, nitrogen was preferentially removed relative to carbon within the DOM pool, then the recalcitrant DOM shows ultimately the high DOC to DON ratio 8. The northwestern Pacific marginal seas, including the East China Sea (ECS) and the southern sea off Korea, are among the largest continental shelves in the world 9. These seas receive huge amounts of freshwater (0.9 × 10 12 m 3 year −1) from the Changjiang River 10 and seawater from the Kuroshio branch water, a strong western boundary current 11. Here, the mixing of freshwater driven by the Changjian...

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Section: Discussionmentioning

confidence: 76%

Factors controlling the distributions of dissolved organic matter in the East China Sea during summer

Kim

Park

et al. 2020

Sci Rep

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“…The variability of the marine organic carbon cycle in a changing climate has been discussed by several papers in this issue [64][65][66][67]; the dynamics of which are related to temporal (seasonal, inter-annual) variations in hydrodynamics, nutrient cycling, and other biogeochemical processes. Continuous monitoring efforts and modelling studies are essential in predicting future changes organic carbon distributions with respect to identified factors.…”

Section: Organic Carbon and The Sustainable Use Of The Environment Anmentioning

confidence: 99%

Organic Carbon Concentrations in High- and Low-Productivity Areas of the Sulu Sea

et al. 2018

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The sequestration of anthropogenic carbon dioxide in the form of organic carbon and its eventual deposition in the sediments is an important component of the marine carbon cycle. In the Sulu Sea, Philippines, organic carbon contents in the sediments have been relatively well studied, but the processes that describe the organic carbon distributions in the water column have not been elucidated. Dissolved and particulate organic carbon (DOC, POC) concentrations were measured at several stations in the Sulu Sea during the northeast monsoon of 2007/2008 to understand the dynamics of organic carbon in this unique internal sea. Analyses of primary productivity estimates, beam attenuation coefficient (at 660 nm) profiles, and correlation coefficients among DOC, POC and other parameters (e.g., apparent oxygen utilization) at different layers of the water column indicate that surface primary productivity, upwelling, bottom intensified flows across sills, and ventilation from shallow sills, which may contain semi-labile DOC that is estimated to largely contribute to microbial respiration in the bathypelagic layer, are the major processes that affect the DOC and POC distributions in the Sulu Sea. The variability of these processes should be taken into consideration when assessing the sustainability of internal and marginal seas as carbon sinks.

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“…The concentration and composition of the particles in the ocean is changing due to higher sediment input from the coastal erosion, high riverine input, changes in terrestrial organic matter input and exponentially increasing amounts of micro-and nanoplastic particles (Rachold et al, 2004;Chen et al, 2012;Jambeck et al, 2015;Basu and Mackey, 2018;Zheng et al, 2018). Further, the ocean chemistry is rapidly changing due to climate change, expansion of oxygen minimum zones and high sediment loads in estuarine and coastal areas.…”

Section: U/th Series Isotope Tracers To Examine the Marine Carbon Cyclementioning

confidence: 99%

Exploring New Frontiers in Marine Radioisotope Tracing – Adapting to New Opportunities and Challenges

et al. 2020

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Radioisotopes have been used in earth and environmental sciences for over 150 years and provide unique tools to study environmental processes in great detail from a cellular level through to an oceanic basin scale. These nuclear techniques have been employed to understand coastal and marine ecosystems via laboratory and field studies in terms of how aquatic organisms respond to environmental stressors, including temperature, pH, nutrients, metals, organic anthropogenic contaminants, and biological toxins. Global marine issues, such as ocean warming, deoxygenation, plastic pollution, ocean acidification, increased duration, and intensity of toxic harmful algal blooms (HABs), and coastal contamination are all impacting marine environments, thereby imposing various environmental and economic risks. Being able to reliably assess the condition of coastal and marine ecosystems, and how they may respond to future disturbances, can provide vital information for society in the sustainable management of their marine environments. This paper summarizes the historical use of radiotracers in these systems, describes how existing techniques of radioecological tracing can be developed for specific current environmental issues and provides information on emerging issues that would benefit from current and new radiotracer methods. Current challenges with using radioecological tracers and opportunities are highlighted, as well as opportunities to maximize the application of these methods to greatly increase the ability of environmental managers to conduct evidence-based management of coastal and marine ecosystems.

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Seasonal Variations of Dissolved Organic Matter in the East China Sea Using EEM-PARAFAC and Implications for Carbon and Nutrient Cycling

Cited by 12 publications

References 57 publications

Factors controlling the distributions of dissolved organic matter in the East China Sea during summer

Factors controlling the distributions of dissolved organic matter in the East China Sea during summer

Organic Carbon Concentrations in High- and Low-Productivity Areas of the Sulu Sea

Exploring New Frontiers in Marine Radioisotope Tracing – Adapting to New Opportunities and Challenges

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